Instructions:

In the now-open explorer windows select this folder:C:\ProgramData\Microsoft\Windows\Start Menu\Programs
(This folder is only visible if previously in Windows Explorer under "Organize" - "Folder and Search Options", tab "View" has switched on "Show hidden files, folders and drives"):

The new toolbar "Programs" appears in the task bar:

Now the classic menu can already open with the small double arrow:

To visually adapt the classic menu a little,
click with the right mouse button into the taskbar
and remove the hook in front of "Lock the Taskbar":

Now a delimiter of the toolbar becomes visible in form of a three times dotted line (red arrow). Right mouse click onto this dotted delimiter and disable "Show text" and disable "Show title" and enable "Large symbols":

This shrinks the toolbar of the classic menu to a yellow folder icon - this is the Accessories folder:

To select another, prettier symbol click again with right mouse button
on the dotted delimiter and select "Open folder":

Choose a link and change it's icon; e.g. make a copy of the link "XPS Viewer"
and change it's icon into green orb symbol out of c:\windows\ehome\ehres.dll

Here in this example a new symbol is assigned to the link "XPS Viewer - Copy" (right mouse click on the link and then select "Properties". In the example a symbol is used from the file c:\windows\ehome\ehres.dll. Many more symbols which already in Windows 7 included are listed on this page:

If the dotted delimiter is dragged to the left
all single folders are shown with their yellow symbols
and at the end the link "XPS Viewer - Copy" with the new green orb symbol:

Now drag the link "XPS Viewer - Copy" with the new green orb symbol to the most left position:

Then drag the dotted delimiter back to the right side until only one symbol remains:

Now drag the leftmost dotted delimiter (near the start button) to the right side.
From a certain position the new toolbar with the Classic menu "jumps" suddenly to the left:

Now you only need to pull the right delimiter back to the left till only the one icon remains.

At least a right mouse click to the taskbar and enabling "Lock the taskbar"
will remove all dotted delimiters:

Remark:

The so arranged classic menu is still not quite complete. Windows managed inC:\ProgramData\Microsoft\Windows\Start Menu\Programs
a menu which includes only the menu entries which are shown to "all users". In addition there is a second folderC:\Users\[user name]\AppData\Roaming\Microsoft\Windows\Start Menu\Programs
with menu entries which are shown only to the "individual user". So the normal start menu is merged together from these two locations.

Here you see the two different folders with different entries
first from "all user", second from "individual user":

The entries "Command Prompt", "Notepad", "Run" and "Windows Explorer" from the individual user folder don't appear in the new classic start menu.

The classic menu described above cannot merge these two locations like the original menu bar. But you can move all menu entries from the "individual user" folderC:\Benutzer\[user name]\AppData\Roaming\Microsoft\Windows\Startmenü\Programme
to the corresponding "all user" folderC:\ProgramData\Microsoft\Windows\Startmenü\Programme
Then you only have one place where all menu entries are stored. And all menu entries are then listed in the new classic menu.